Individuals with Williams syndrome (WS) have an unusual cognitive profile characterized by visuospatial processing deficits but strengths in face processing, language, and hypersociability. Project V seeks to understand the cognitive processing of WS through the achievement of the following specific aims: Aim 1- Characterization and Expansion of the WS Cognitive Phenotype: We will continue in our successful strategy of administering a core battery of standardized measures of cognitive functioning to groups of WS, normal controls, and individuals with non-specific mental retardation. Our core battery provides the basis for cross-level analyses linking cognition to its cerebral and genetic underpinnings, with special attention paid to individuals with special deletions and differing parent of origin. Aim 2 - Understanding the Processing Bases of Neurocognitive Dissociations in WS. Based on our latest work, and converging information across projects, we have identified three interrelated domains that we believe present the optimal potential for understanding WS cognitive processes: a) Spatial Deficit. Experiments focus on dorsoventral and posterior/anterior processing gradients, including a new investigation of a supramodal spatial deficit by studying auditory localization and auditory-visual sensory integration, b) Face Processin.q Strength. Experiments will help clarify the nature of this relative strength in WS, emphasizing early visual processing influences, face-specific processing strategies, and top-down processing influences, c) Affiliation: Lan.qua.qe, Affect and Empathy. Studies will investigate language and affect processing in coordinated studies with Projects II and III. Aim 3 - Mapping the Cognitive Phenotype to its Neural and Genetic Bases. This Aim is achieved through the coordinated design of studies across Projects I-V. Recent advances across all projects have led to tightly integrated studies addressing identical hypotheses that will provide an unprecedented opportunity for increasing our understanding of the neural and genetic bases of cognition in WS. Summary. This renewal tests exciting new hypotheses linking genetics (e.g., imprinting and deletion size) and neural systems (e.g., cell size and density, overactivity and enlargement of amygdala, etc) to the cognitive phenotype of WS.